Biased blind side temporary fasteners are used primarily to hold at least one work piece, commonly a panel-type material, in registry with another work piece, each defining at least one commonly aligned hole through which the fastener may at least partially pass. Once the two or more work pieces are so aligned and retained, they may be subject to subsequent material processing, e.g., welding, permanent fastening, etc. Examples of environments wherein such fasteners are commonly used include the aerospace and automotive industries.
A common form of such fasteners is the “CLECO” fastener, an example of which can be found in U.S. Pat. No. 4,537,542. In such fasteners, a static central projection anchored to opposing wall portions of the fastener case separates a pair of legs that axially translate about the projection in the working region of the fastener. Depressing a plunger causes the legs to translate along the projection until the distal ends thereof clear the projection, thereby permitting those portions of the legs to collapse toward each other, effectively modifying the external diameter of the distal ends. A spring interfaces with the plunger and the case to resist the plunger depression; the legs are linked to the plunger and therefore assume a clamped state as a nominal state when the spring is permitted to fully extend within the limits of its enclosure.
While this style of fastener may be adequate in certain situations, e.g., low tolerance material processing, the legs are at best only partially hemispherical, which fails to address issues of lateral play between the work pieces when compressively held together by the fastener. Moreover, such fasteners are more likely to react negatively to work piece rotation given the inclusion of three or more elements that are not mechanically linked to each other (there is intentional “float” between all components to permit translation of the legs relative to the projection, but this float is subject to very little restraint in the plane of the projection).